U.S. patent number 8,457,618 [Application Number 12/483,843] was granted by the patent office on 2013-06-04 for preventing random access based on outdated system information in a wireless communication system.
This patent grant is currently assigned to Motorola Mobility LLC. The grantee listed for this patent is Richard C. Burbidge, Ravi Kuchibhotla, Murali Narasimha. Invention is credited to Richard C. Burbidge, Ravi Kuchibhotla, Murali Narasimha.
United States Patent |
8,457,618 |
Narasimha , et al. |
June 4, 2013 |
Preventing random access based on outdated system information in a
wireless communication system
Abstract
A method for preventing random access by a mobile station with
outdated system information includes, in the mobile station,
receiving system information earlier than a time instant at which
the system information become effective, determining that a current
time is within a new access blocking offset before the time instant
at which the system information becomes effective, and delaying
random access at least until the time instant at which the system
information becomes effective.
Inventors: |
Narasimha; Murali (Lake Zurich,
IL), Burbidge; Richard C. (Hook, GB), Kuchibhotla;
Ravi (Gurnee, IL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Narasimha; Murali
Burbidge; Richard C.
Kuchibhotla; Ravi |
Lake Zurich
Hook
Gurnee |
IL
N/A
IL |
US
GB
US |
|
|
Assignee: |
Motorola Mobility LLC
(Libertyville, IL)
|
Family
ID: |
41431761 |
Appl.
No.: |
12/483,843 |
Filed: |
June 12, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090318128 A1 |
Dec 24, 2009 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61074211 |
Jun 20, 2008 |
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Current U.S.
Class: |
455/418;
455/414.1 |
Current CPC
Class: |
H04W
48/16 (20130101); H04W 74/08 (20130101) |
Current International
Class: |
H04M
3/00 (20060101); H04M 3/42 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1553797 |
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Jul 2005 |
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EP |
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2004064272 |
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Jul 2004 |
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WO |
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2007049204 |
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May 2007 |
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WO |
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2007133034 |
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Nov 2007 |
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WO |
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Other References
Panasonic "TP for System Information Change Notification" 3GPP TSG
RAN WG2 #62, R2-082835; May 5-9, Kansas City, USA; 8 pages. cited
by applicant .
Nokia "System Information Scheduling--Clarifications" 3GPP TSG RAN
WG2 Meeting #60bis, R2-080156; Jan. 14-18, 2008 Seville, Spain; 4
pages; XP50138036. cited by applicant .
Huawei "System Information Change Issues" 3GPP TSG RAN WG2 #61bis;
R2-081636; Mar. 31-Apr. 4, Shenzhen, China; 2 pages; XP50139359.
cited by applicant .
Motorola "System Information Change During Connection Setup
Procedure" 3GPP TSG-RAN WG2#63, R2-084212; Aug. 18-22, 2008, Jeju
Korea; 14 pages; XP50319335. cited by applicant .
PCT Search Report; PCT Application No. PCT/US2009/047720; Oct. 13,
2009; 15 pages. cited by applicant .
3GPP TSG RAN WG2 RRC adhoc Jun. 5-6, Sophia ANtipolis, France
RS-082942. cited by applicant .
Mexican Patent Office "Substantive Examination" for Mexican Patent
Application No. 102648 (CS36024) dated Nov. 27, 2012, 2 pages.
cited by applicant.
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Primary Examiner: Bost; Dwayne
Assistant Examiner: Kohlman; Christopher
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims benefits under 35 U.S.C. 119(e) from
U.S. provisional Application No. 61/074,211 filed on 20 Jun. 2008,
the contents of which are incorporated herein by reference.
Claims
What is claimed is:
1. A wireless communication mobile station for preventing random
access with outdated system information, the mobile station
comprising: a transceiver coupled to a processor, the processor
configured to cause the transceiver to receive system information
earlier than a time instant at which the system information becomes
effective; the processor configured to determine that a current
time is within a new access blocking offset before the time instant
at which the system information becomes effective; and the
processor configured to delay random access at least until the time
instant at which the system information becomes effective.
2. The mobile station according to claim 1 wherein the time instant
at which the system information becomes effective coincides with a
start time of a modification period.
3. The mobile station according to claim 1 wherein the time instant
at which the system information becomes effective is later than a
start time of a modification period.
4. The mobile station according to claim 1, the processor
configured to cause the transceiver to receive modified system
information wherein a duration by which the reception of the
modified system information is received from the base station
precedes the time instant at which the system information becomes
effective.
5. The mobile station according to claim 1, the processor
configured to determine that a current time is within a new access
blocking offset before the time instant at which the system
information becomes effective by determining that a current time is
prior to the new access blocking offset before the time instant at
which the system information becomes effective, and the processor
configured to continue random access using the system information
valid at the current time.
6. The mobile station according to claim 1 the processor configured
to determine that the received system information is modified
system information.
7. The mobile station according to claim 1, the processor
configured to cause the transceiver to receive a system information
changing indication.
8. A wireless communication base station, the base station
comprising: a transceiver coupled to a processor, the processor
configured to cause the transceiver to transmit modified system
information earlier than a time instant at which the modified
system information becomes effective, and the processor configured
to indicate to a mobile station that start of an access attempt is
not allowed until after a new access blocking offset prior to the
time instant at which the modified system information becomes
effective.
9. The base station according to claim 8 wherein the time instant
at which the modified system information becomes effective
coincides with a start time of a modification period.
10. The base station according to claim 8 wherein the time instant
at which the system information becomes effective is later than a
start time of a modification period.
11. The base station according to claim 8, the processor configured
to cause the transceiver to transmit a system information change
indication concurrently with transmission of the modified system
information.
12. The base station according to claim 8 wherein the modified
system information further includes for a finite duration a system
information changing indication.
13. The base station according to claim 8 wherein a duration by
which the transmission of the modified system information precedes
the time instant at which the modified system information becomes
effective is transmitted by the base station.
14. A wireless communication device comprising: a transceiver; a
controller coupled to the transceiver, the controller configured to
decode system information received by the transceiver and to obtain
modified system information prior to a time instant at which the
modified system information becomes effective, and the controller
configured to delay a connection establishment attempt when a
connection establishment attempt could result in an access attempt
using outdated system information.
15. The wireless communication device according to claim 14,
wherein the controller is configured to determine that a connection
establishment attempt could result in an access attempt using
outdated system information by determining that a current time is
less than a new access blocking offset prior to the time instant at
which the modified system information becomes effective.
16. The wireless communication device according to claim 14,
wherein the controller is configured to indicate that reselection
has occurred.
17. The wireless communication device according to claim 14, the
controller is configured to determine that the system information
transmitted by the base station is effective at a later time and to
delay a connection establishment attempt until the system
information becomes effective.
18. The wireless communication device according to claim 16,
wherein the controller is configured to determine if the system
information is effective at a later time by determining that the
current time is within an offset of an effective period prior to a
time instant at which the system information becomes effective, and
receiving a system information change indication on the paging
channel.
19. The wireless communication device according to claim 16,
wherein the controller is configured to determine if the system
information is effective at a later time by determining that the
current time is within an offset of effective period prior to a
time instant at which the system information becomes effective, and
the controller is configured to decode a system information
changing indication from the system information.
Description
FIELD OF THE DISCLOSURE
The present disclosure relates generally to wireless communications
and, more specifically, to preventing random access in a wireless
communication system that provides updated system information
messages, network entities, user terminals and corresponding
methods.
BACKGROUND
System information in Third Generation Partnership Project (3GPP)
Universal Mobile Terrestrial System (UMTS) Long Term Evolution
(LTE) systems includes parameters needed by a wireless
communication mobile station (MS), hereafter also referred to as
user equipment (UE), for correct operation. This information is
grouped into different information blocks including a Master
Information Block (MIB) and several System Information Blocks
(SIB). Generally, UEs are expected to use the currently valid
system information set at all times. To manage changes of system
information (SI), the notion of a modification period is used. When
the network needs to change a SI parameter, a change indication is
first transmitted for a duration known as a modification period.
The actual changed SI is transmitted in a subsequent modification
period. This framework ensures that a UE in idle mode or in
connected mode gets an indication of the SI change and subsequently
reads the changed SI. However, if a SI change occurs when a UE is
attempting to establish a connection, the UE may use old SI.
Potential problem scenarios are discussed below where the SI change
period and radio resource control (RRC) connection establishment
overlap. The first scenario resulted from a discussion of 3GPP
technical document R2-082942.
In one scenario illustrated in FIG. 1, a UE receives an SI change
indication and a page at the same time. Alternatively, a similar
problem arises if the UE decides to originate very shortly after
receiving a SI change indication. The ensuing random access channel
(RACH) attempts cross the modification period boundary and because
of the time required for the UE to read SI, a UE RACH attempt that
occurs after the modification period boundary will use old SI. This
may be problematic as the PHICH duration or resource may have
changed leading to failure after the UE enters connected mode. The
same problem results, though less frequently, from the following
circumstances: a change of other MIB parameters; cell barring
status may have changed; a change in time division duplex (TDD),
UL/DL split; a change in the RACH parameters (e.g., root sequence,
PRACH resources, preamble split, random access (RA) response
window, preamble_trans_max, . . . ) leading to failed RACH attempts
and interference to other UEs; access class barring may have been
switched on which the UE would be violating.
In another scenario illustrated in FIG. 2, a UE originates in a
modification period where the SI is being modified, but the
origination is started before the UE's paging occasion, so the UE
is unaware of the SI change at the time of origination. This
scenario requires the UE to continue monitoring paging for the SI
change indication, which is contrary to Proposal 1 of 3GPP
technical document R2-082942. Assuming that the UE receives the SI
change indication, the UE still cannot receive the changed SI and
all the problems mentioned above are possible.
In yet another scenario illustrated in FIG. 3, a UE interrupts RACH
attempts when the modification period boundary is reached, and the
UE reads the new SI, and then restarts the RACH attempts.
Particularly, at the modification period boundary the UE suspends
T300 and starts reading MIB, SIB1, SIB2. After the modification
period boundary, the UE does not RACH until reading MIB, SIB1,
SIB2. After the modification period boundary, UE does not
receive/act on a RACH response until a RACH is sent after reading
MIB, SIB1, SIB2. This is to avoid the following situation where the
UE sends the RACH before the modification period boundary, and
receives a RACH response with an UL grant after the modification
period boundary. The UE should not send message 3 before reading
SI, but the UL grant is not valid for that long. So the UE has to
simply ignore the RACH response. The UE sends the RACH again after
reading MIB, SIB1, SIB2. In FIG. 3, the UE restarts T300 and
continues the RACH procedure after reading MIB, SIB1 & SIB2.
The problem with this solution is that each time there is a SI
change no UE can perform any UL transmissions until reading the SI.
Reading the SI can take more than a second and .about.300 ms for
the most critical information. This duration then becomes a
blackout period for the system resulting in wasted capacity and
delay to various applications in UE. This problem becomes
particularly acute when the SI is changed relatively frequently for
load management purposes during peak hours.
The various aspects, features and advantages of the disclosure will
become more fully apparent to those having ordinary skill in the
art upon careful consideration of the following Detailed
Description thereof with the accompanying drawings described below.
The drawings may have been simplified for clarity and are not
necessarily drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a first prior art system access process time
line.
FIG. 2 illustrates a second prior art system access process time
line.
FIG. 3 illustrates a third prior art system access process time
line.
FIG. 4 illustrates an alternative system access process time
line.
FIG. 5 illustrates another alternative system access process time
line.
DETAILED DESCRIPTION
Two embodiments are provided that address the problematic use of
old system information without causing the blackout period
described above.
FIG. 4 illustrates an effective period offset approach. In the
first embodiment the new MIB, SIB1 & SIB2 are transmitted
"Offset of Effective Period" before the modification period where
the new SI is effective. After a time "New Access blocking offset"
prior to the new SI effective period, the UE radio resource control
(RRC) is disallowed from starting access procedure. Previously
started accesses are allowed to continue. If a UE RRC starts a new
access after the "New Access Blocking Offset" and then sees an SI
change indication, then the UE aborts its access attempt. UEs that
enter the cell in the interval when the new SI is transmitted
before it is effective wait until the effective time before
accessing. Such a UE reads SI (at least MIB, SIB1, SIB2) to get
modification period boundary and "Offset of Effective Period"
information. The UE then checks for a SI change indication. If an
SI change is being indicated, the UE waits at least until the SI
effective period before new SI is used.
FIG. 5 illustrates an offset between the modification period and
the SI effective period approach. In this embodiment, an offset is
introduced between the modification period and the SI effective
period (SI effective period is later than the modification period
by "Offset of effective period"). After time "New Access blocking
offset" prior to the new SI effective period, UE RRC is disallowed
from starting access procedure. Previously started accesses are
allowed to continue. A 1 bit "SI-changing" indication is included
in the MIB. This is turned on in the first modification period
where new SI is transmitted. UEs that enter the cell in the
interval when the new SI is transmitted before it is effective wait
until the effective time before accessing. Such a UE reads MIB and
finds the "SI changing" indication to be on. The UE then reads SIB1
(and SIB2) to get a modification period and an "Offset of effective
period", and the UE determines if it is within "Offset of effective
period" prior to the next SI effective period. If the UE is within
the "Offset of effective period", the UE waits at least until the
SI effective period before using the new SI.
While the present disclosure and the best modes thereof have been
described in a manner establishing possession and enabling those of
ordinary skill to make and use the same, it will be understood and
appreciated that there are equivalents to the exemplary embodiments
disclosed herein and that modifications and variations may be made
thereto without departing from the scope and spirit of the
inventions, which are to be limited not by the exemplary
embodiments but by the appended claims.
* * * * *